The present invention relates to a method for preparing an extract comprising a mixture of madecassoside, of terminoloside and, where appropriate, of asiaticoside, an extract of Centella asiatica comprising more than 75 wt % of a mixture of medecassoside, of terminoloside and of asiaticoside, relative to the total weight of the extract, and an extract of Centella asiatica comprising more than 95 wt % of a mixture of madecassoside and of terminoloside relative to the total weight of the extract, and to their use for regulating inflammatory mechanisms.
Centella asiatica, also known as Violette marronne (Reunion island), as Gotu Kola or as Indian pennywort (India), or as Centella repanda (North America) and as Talapetraka (Madagascar), is a polymorphous herb that grows in the wild in humid and shady regions at an ideal altitude of 600 meters.
Centella asiatica belongs to the family of Umbelliferae (Apiaceae), particularly to the Hydrocotyle subfamily. Centella corresponds to the name of the genus of the plant, while asiatica corresponds to its species. Centella asiatica includes three varieties called Typica, Abyssinica and Floridana. Centella asiatica has been known and used in Madagascan, Indian, Chinese, American Indian or Indonesian medicine for more than 3000 years. It has varied and diverse uses according to countries. It is particularly advantageous for its healing, sedative, analgesic, antidepressant, antiviral and antimicrobial properties. It is generally used topically or orally. Paradoxically, the appearance of Centella asiatica in modern western medicine was late, since it made its entry into the Codex only in 1884, and the first dry extract was produced only in 1941.
The active agents of Centella asiatica are pentacyclic triterpenes, which are in the form of genins; these are asiatic acid (formula I) and madecassic acid (formula II), and of heterosides; these are asiaticoside (formula III) and madecassoside (formula IV).

Asiaticoside, madecassoside, asiatic acid and madecassic acid molecules contribute to the plant's natural defences. In order to be able to satisfactorily exploit the active agents of Centella asiatica industrially, it is therefore essential to collect the plant in the wild state, an environmental stress being necessary for this hardy plant to have a high triterpene content.
The Centella asiatica heterosides, madecassoside and asiaticoside, are sugar-containing complexes which constitute the storage forms of madecassic and of asiatic acid of the plant, synthesized essentially in the wet season. A bacterial, yeast or fungal attack on the plant activates the genin-releasing hydrolases. Triterpene molecules are particularly advantageous because of their regulatory and activating action on collagen synthesis. The genins and heterosides extracted from Centella asiatica promote in particular the synthesis of collagens 1 and 3. These active agents are used in the pharmaceutical field mainly for facilitating healing and in the treatment of venous insufficiency. They are used in the cosmetics field mainly as antiwrinkle and anticellulite agents. The active agents of Centella asiatica most commonly used in the prior art are asiatic acid and madecassic acid, and also asiaticoside. Since madecassoside is highly water-soluble, it is most commonly entrained in the washing water during conventional methods for extracting liposoluble active agents.
The methods of the prior art make it possible to obtain a mixture of asiaticoside and of madecassoside. This mixture comprises approximately 25 wt % of asiaticoside, 60 wt % of macecassoside and 15 wt % of by-products, mainly consisting of fatty acids and of osides, relative to the total weight of the mixture. Other methods of the prior art also make it possible to obtain madecassoside that is 81 wt % pure, relative to the total weight of the extract, said extract also comprising close isomers of madecassoside, fatty acids, mainly linoleic acid, linolenic acid, palmitic acid or oleic acid, and sugars such as osides.
Surprisingly, the applicant has developed a novel method of extraction which makes it possible to obtain a mixture of madecassoside, of asiaticoside and of a novel molecule that has been called terminoloside, said mixture being more than 75 wt % pure relative to the total weight of the mixture, and to obtain a mixture of madecassoside and of terminoloside, obtained more than 95 wt % pure relative to the total weight of the mixture. Similarly, the applicant has discovered an extract of Centella asiatica comprising a mixture of madecassoside, of terminoloside and, where appropriate, of asiaticoside.
Surprisingly, the applicant has also discovered that the mixture of madecassoside and of terminoloside extracted from the parts of Centella asiatica that are above ground can be used in a drug for regulating inflammatory mechanisms.
In addition, the mixture of madecassoside, of terminoloside and of asiaticoside extracted from the parts of Centella asiatica that are above ground can be used in a cosmetic composition for preventing and delaying premature aging of the skin.